Hurricane Harvey provides lab for U.S. forecast experiments

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For years, U.S. forecasters have envied their colleagues at the European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading, U.K., whose hurricane prediction models remain the gold standard. Infamously, the http://www.billigaflygbiljetter.nu/forum/allman-resediskussion/space-jam-air-jordan-11s-are-restocking-this-friday-952National Weather Service (NWS) in 2012 failed to predict Hurricane Sandy's turn into New Jersey, whereas ECMWF was spot on. But two innovations tested during Hurricane Harvey, one from NASA and another from the National Oceanic and Atmospheric Administration (NOAA), could help level the playing field. NOAA's offering is a brand-new forecasting model. Two years ago, NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey, won a competition to provide computer code for the next-generation weather model. Current NWS models must wait for results from a time-consuming global simulation before they can zoom in on a smaller area and run a high-resolution model for hurricanes. GFDL's new code can simulate storms at the same time as it runs globally. That should improve forecasts for hurricane http://templatedevelopers.grou.ps/talks/7769212paths because the model's fine-scaled predictions can feed immediately into its next run, rather than lagging behind. Last week, GFDL anxiously watched the developing storm to see how it compared with a test run of its model. That Thursday, a day prior to landfall, the experiment agreed with the European model that Harvey would plow inland, stall, then head back out over the Gulf of Mexico before making a second landfall near Houston, Texas. That progression, close to what was happening at press time, explains the sustained, catastrophic rainfall that has battered the Texas coast. The GFDL model, called FV3, also correctly forecasted that Harvey would develop a double eyewall—a second circular band of storms around the band enclosing the eye. The model's zoomed-in view also predicted the extreme rainfall totals seen by Houston some 5 days in advance, says Shian-Jiann Lin, the GFDL scientist who led the development of FV3. Caution should be taken with the results, says Chris Davis, a meteorologist at the National Center for Atmospheric Research in Boulder, Colorado. “I do not believe meaningful conclusions about model performance can be reached for a single storm.” Still, Lin says, “If you http://huaxi.labsky.com/forum/forum_posts.asp?TID=67974&PN=1&TPN=1count the full history of Harvey … I think FV3 global is likely the top performer.” FV3 will probably start powering U.S. forecasts next year.